From 2314247918132f1ce8804e53d4c68bf14e485661 Mon Sep 17 00:00:00 2001
From: The MMGen Project <mmgen@tuta.io>
Date: Fri, 6 May 2022 12:52:41 +0000
Subject: [PATCH] add `msys2-sshd-setup.sh` convenience script

---
 scripts/msys2-sshd-setup.sh | 62 +++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 scripts/msys2-sshd-setup.sh

diff --git a/scripts/msys2-sshd-setup.sh b/scripts/msys2-sshd-setup.sh
new file mode 100644
index 00000000..62c8892d
--- /dev/null
+++ b/scripts/msys2-sshd-setup.sh
@@ -0,0 +1,62 @@
+#!/bin/sh
+#
+# msys2-sshd-setup.sh — configure sshd on MSYS2 and run it as a Windows service
+#
+# Replaces ssh-host-config <https://github.com/openssh/openssh-portable/blob/master/contrib/cygwin/ssh-host-config>
+# Adapted from <https://ghc.haskell.org/trac/ghc/wiki/Building/Windows/SSHD> by Sam Hocevar <sam@hocevar.net>
+# Adapted from <https://gist.github.com/samhocevar/00eec26d9e9988d080ac> by David Macek
+#
+# Prerequisites:
+#   - pacman -S openssh cygrunsrv
+#
+#
+# Adapted by the MMGen Project from https://www.msys2.org/wiki/Setting-up-SSHd/
+#
+# MMGen notes:
+#    Open PowerShell (Run as Administrator)
+#    system32> net user administrator /active:yes
+#    system32> C:\\msys64\usr\bin\bash.exe --login
+#    $ path/to/msys2-sshd-setup.sh
+#
+#    Now the SSH service should start automatically when Windows is rebooted.
+#    You can manually start and stop the service by running:
+#        net start msys2_sshd
+#        net stop msys2_sshd
+
+set -e
+
+# Configuration
+UNPRIV_USER=sshd # DO NOT CHANGE; this username is hardcoded in the openssh code
+UNPRIV_NAME="Privilege separation user for sshd"
+EMPTY_DIR=/var/empty
+
+# Check installation sanity
+if ! cygrunsrv -v >/dev/null; then
+    echo "ERROR: Missing 'cygrunsrv'. Try: pacman -S cygrunsrv."
+    exit 1
+fi
+
+if ! ssh-keygen -A; then
+    echo "ERROR: Missing 'ssh-keygen'. Try: pacman -S openssh."
+    exit 1
+fi
+
+# The unprivileged sshd user (for privilege separation)
+add="$(if ! net user "${UNPRIV_USER}" >/dev/null; then echo "//add"; fi)"
+if ! net user "${UNPRIV_USER}" ${add} //fullname:"${UNPRIV_NAME}" \
+              //homedir:"$(cygpath -w ${EMPTY_DIR})" //active:no; then
+    echo "ERROR: Unable to create Windows user ${UNPRIV_USER}"
+    exit 1
+fi
+
+# Add or update /etc/passwd entries
+if test -f /etc/passwd; then
+    sed -i -e '/^'"${UNPRIV_USER}"':/d' /etc/passwd
+    SED='/^'"${UNPRIV_USER}"':/s?^\(\([^:]*:\)\{5\}\).*?\1'"${EMPTY_DIR}"':/bin/false?p'
+    mkpasswd -l -u "${UNPRIV_USER}" | sed -e 's/^[^:]*+//' | sed -ne "${SED}" >> /etc/passwd
+    mkgroup.exe -l > /etc/group
+fi
+
+# Finally, register service with cygrunsrv and start it
+cygrunsrv -R msys2_sshd || true
+cygrunsrv -I msys2_sshd -d "MSYS2 sshd" -p /usr/bin/sshd.exe -a "-D -e" -y tcpip